Sensors used for controlling the automatic sensing faucets and other equipment (such as urinals or toilets) in the kitchen or washroom are usually infrared sensors. A traditional infrared sensor comprises an infrared emitting device and infrared receiving device. The traditional infrared sensor conventionally continuously emits infrared light to the detected area at regular time intervals, such as emitting once every 0.3 second, and said infrared receiving device receives the reflected infrared signals. By checking the intensity of the received infrared signals, a controller determines whether the equipments in the kitchen or washroom are in use. The use determination is used to control the equipment, for example, by the opening or closing of a valve for the automatic sensing faucet or for the flushing of the urinals. The following is an example of how such a conventional infrared sensor system is used for controlling the faucet. When the infrared sensor system detects that the user enters the detected area, the valve of the faucet is opened to discharge water. When the infrared sensor detects that the user has left the detected area, the valve of the faucet is closed to stop the water flow. When such an infrared sensing system is used for controlling the urinal the following is an example of the behavior: when the infrared sensor detects that the urinal is in use, the water discharging valve is opened for the first flush and when the infrared sensor detects that the user has left the detected area, the water discharging valve is opened for the last flush.
As the traditionally automatic sensing faucets use direct current power, how to reduce the power consumed by the infrared sensor (and thereby extend the life of the battery) becomes a challenging technical problem. In order to save power, some existing systems attempt to improve upon of the traditional infrared sensor systems described above. In such existing systems, during normal use the infrared sensor emits infrared light at a relatively low frequency for detection. If the system determines that a user is using the equipment in the kitchen or washroom, the infrared sensor emits infrared light at higher frequency. Such existing methods are not effective at saving power and are inconvenient to the user. For example, when the infrared sensor is used to control the faucet, the user may have to wait for a long time before the water comes out from the faucet due to the relatively low frequency infrared light sampling. What is needed is an automatic sensing system which is more effective and consumes less power.